A filter is described in the German Auslegeschrift DE-AS No. 25 06 359, having a bomb-shaped (i.e., closed and rounded at one end) filter housing, which is attached by means of a collar piece to an inlet and outlet head comprising an inlet duct and an outlet duct. A filter element is screwed into the head component by means of a threaded component. The threaded component possesses windows, which form a communication between the inlet duct and the internal space of the threaded component and filter cartridge. A further end cap is connected to the threaded component by means of a tension rod. The inlet and outlet head is sealed from the threaded component by an annular seal and also from the filter housing by an annular seal.
In filters of this type, the filter medium becomes dirty and must either be cleaned or replaced by a new filter medium. For filter media that can be cleaned, cleaning cannot be repeated an unlimited number of times, so that such filter media also must be replaced after a certain time. Depending upon the particular form of construction, the entire filter must be changed.
A filter is described in German Offenlegungshcrift DE-OS No. 27 06 017; wherein a hollow cylindrical filter element extends between an upper and a lower cover. The upper cover is furnished with a central opening, which is shaped to form an external thread extending coaxially to the hollow cylinder. A sealing ring situated between the upper cover and the external thread ensures that the region in which the medium to be filtered is situated is sealingly separated from the region in which the purified medium is situated.
In this filter, the upper and lower covers are firmly connected to the filter element, so that what was stated above in regard to the filter described in DE-AS No. 25 06 359 applies here also, to the effect that after a specific degree of fouling has been reached, the filter in total must be removed and replaced by a new filter. This is laborious and increases the costs to the operator.
The task underlying the present invention is to create a filter, in which the separate filter components can be separated without difficulty from one another and the fouled filter element can be replaced by a new one in a simple manner. This task is achieved according to the present invention in that a sealing ring is situated each on the upper and the lower end face of the filter element.
According to a further feature of the invention, the sealing rings are firmly connected to the filter element. It is to be recommended here that the sealing rings shall be embedded in a grouting compound, for example epoxy resin. The sealing rings should lie in grooves, the side walls of which grip around the rings in the manner of claws. The sealing rings therefore do not develop any springing action during pulling out. With attendant advantage, the epoxy resin forms a profile ring in the region of the sealing rings in such a manner that the two end regions of the filter tube fit with only slight tolerance into the grooves of the upper and lower cover. The cover may be formed as an adapter for a filter housing or may be a component of the filter housing. In the filter of this invention, the metal end caps are omitted in favour of the epoxy ring.
In this manner, a filter element is obtained, which can be removed without difficulty after a specific degree of fouling has been reached and replaced by a new one. It is therefore a throw-away component. If the sealing rings are firmly connected to the filter tube, then there is no risk of a sealing ring being forgotten in the assembly or insertion of a new filter tube.
In the filter of this invention, the covers and the tension rod are retained, which leads to lower operating costs.